Question: What is wrong with this code?!

I've read it again... and again... and again. It's a very simple calculator program, why is this not working? > with(Maplets[Elements]): > MapleCalculator:=Maplet > [ > ["Field 1", TextField['TF1'](10)] > , > ["Field 2", TextField['TF2'](10)] > , > [Button ("Calculate", Evaluate('TF3' =('TF1' + 'TF2'))] > , > ["Value: ", "TextField['TF3'](10)] > ]: > Maplets[Display](MapleCalculator); Error, `]` unexpected
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